Effect of ambrein on smooth muscle responses to various agonists

The pharmacological effects of ambrein (isolated from ambergris) on the contractile responses induced by some agonists in smooth muscle preparations were investigated. Ambrein in the concentration range of 10, 50 and 250 μg/ml decreased the spontaneous contraction of the isolated rabbit jejunum, rat uterus and guinea-pig vas deferens. Ambrein-induced antagonism to acetylcholine (Ach) in the guinea-pig ileum was abolished when the concentration of calcium chloride in the Tyrode's solution was increased to 5 mM/l. Furthermore, ambrein did not antagonise nicotine-induced contractions in the isolated rabbit jejunum or serotonin-induced contractions in the isolated guinea-pig ileum and vas deferens or the rat uterus. However, ambrein in the concentration range of 10, 50 and 250 μg/ml antagonised prostaglandins (PGs) E₂, D₂, F_2α, and oxytocin-induced contractions in the rat uterus in vitro. Ambrein also antagonised (±) noradrenaline and (−) adrenaline-induced contractions in the isolated guinea-pig vas deferens. It is concluded that ambrein-induced non-selective dose-dependent antagonism to the effects of some agonists (Ach, adrenaline, noradrenaline, PGs and oxytocin) in some smooth muscles may be due to the ability of this compound to interfere with the mobilisation of extracellular Ca²⁺ required for muscular contractions induced by these agonists.     

Effects of crinum glaucum aqueous extract on intestinal smooth muscle activity

Crinum glaucum aqueous extract (1–8 mg/mL) produced a concentration dependent, non-competitive inhibition of contractions induced by acetylcholine (1.1 × 10⁻⁸–3.3 × 10⁻⁷M ) and calcium chloride (CaCl₂, 0.05–2 mM ) on the rat duodenum. Contractions of the guinea-pig ileum induced by acetylcholine (1.1 × 10⁻⁸–3.3 × 10⁻⁷M ) and histamine (1.1 × 10⁻⁸–3.3 × 10⁻⁷M ) were inhibited by the extract (1–4 mg/mL). The extract (0.125–2.0 mg/mL) also, produced a concentration dependent relaxation of the guinea-pig taenia coli, precontracted with potassium chloride (40 mM ). It is concluded that the extract is a non-specific relaxant of the gastrointestinal smooth muscles used. © 1998 John Wiley & Sons, Ltd.     

Different Effects of Some Isoquinoline Alkaloids from Argemone mexicana on Electrically Induced Contractions of Isolated Guinea-pig Ileum

The present study examines the effects of the extracts [petroleum ether, CHCl₃, CHCl₃/MeOH (9:1) and MeOH], partially purified fractions and pure compounds from Argemone mexicana on the electrically induced contractions of the isolated guinea-pig ileum (E.C.I.). The results of the experiments indicate that CHCl₃/MeOH (9:1) and MeOH extracts, tested at a concentration of 400, 200 and 100 μg/mL, dose-dependently reduced the guinea-pig ileum contractions, whereas the petroleum ether and CHCl₃ extracts did not affect it. Furthermore, the partially purified fractions II–V from the MeOH extract, each tested at concentrations of 200, 100 and 50 μg/mL also inhibited E.C.I. Finally the pure compounds 1–2 (5×10⁻⁶–1×10⁻⁵–5×10⁻⁵ M ) isolated and purified from the above fractions significantly reduced, in a dose dependent manner, the electrical contractions of the ileum, whereas compound 3 (5×10⁻⁶–1×10⁻⁵×10⁻⁵ M ) increased them. Since the active compounds 1–3 were respectively identified as protopine, allocryptopine and berberine by NMR, the observed effects could be related mainly to these compounds. © 1997 by John Wiley & Sons, Ltd.     

Inhibitory effects of Cistus populifolius on contractile responses in the isolated rat duodenum

The medicinal plant Cistus populifolius L., shows an important dose-dependent spasmolytic activity. The ability of the Cistus extract to inhibit both acetylcholine (ACh) (3.4 × 10⁻⁸–6.8 × 10⁻⁵ M) and CaCl₂ (2 × 10⁻⁴–1.28 × 10⁻² M) -induced contractions and the relaxing effect on K⁺ (75 mM) -induced contractions may indicate a non-specific receptor antagonist. However, this action may be related to the influx of extracellular Ca²⁺. These antispasmodic effects are partly consistent with the use of C. populifolius in folk medicine for certain gastrointestinal disorders.     

Involvement of calcium in the cardiac depressant actions of a garlic dialysate

In order to elucidate a possible role for calcium on the negative cardiotropic effects of a garlic (Allium sativum L., Liliaceae) dialysate in rat atria we studied: (a) the effects of our extract 15 min after preincubation with high and low concentrations of extracellular calcium ([Ca²⁺]_o) on left and right activity of rat atria. The negative inotropism of garlic dialysate increased with calcium 0.75 mM; in contrast, high level of calcium (4.5 mM) induced a significant reduction of this depressant effect. None of these treatments modified the negative chronotropism of garlic; (b) nifedipine (10⁻⁹ to 10⁻⁷ M), verapamil (10⁻⁹ to 10⁻⁷ M) and diltiazem (10⁻⁹ to 10⁻⁷ M) induced a concentration-depe synergism of the log concentration-effect curve of garlic dialysate on left atria. Verapamil and diltiazem (10⁻⁷ M), but not nifedipine increased the inhibitory chronotropism of garlic in right atria; (c) negative inotropic and chronotropic effects demonstrated by nifedipine (1 × 10⁻¹⁰ to 1.1 × 10⁻⁶ M) were antagonized as expected by preincubation with Bay K-8644. Depressant actions of garlic were not modified with this pretreatment. These results suggest that the negative inotropic effect of our garlic dialysate is related to [Ca²⁺]_o availability. It is possible that a restriction of intracellular calcium contributes to this effect. However, the negative chronotropic effect of garlic is scarcely affected by these modifications.     

Pharmacological studies of Striga senegalensis Benth (Scrophulariaceae) as an abortifacient

The methanol extract of Striga senegalensis Benth (Scrophulariaceae) was investigated on isolated rat uterus. Acetylcholine and the methanol extract of the plant produced dose related contractions of smooth muscle of the isolated rat uterus in vitro. Atropine in doses of 2 × 10⁻² to 32 × 10⁻² μg/mL antagonized dose dependently the contraction of the isolated rat uterus produced by both acetylcholine (1.6 × 10⁻¹ μg/mL) and the methanol extract (160 μg/mL). © 1998 John Wiley & Sons, Ltd.     

Vasodilator Effects of the Extract of the Leaves of Cistus populifolius on Rat Thoracic Aorta

The effects of different extracts of Cistus populifolius L. on smooth muscle were studied. The aqueous extract inhibited in a dose dependent manner the noradrenaline (NA) (10⁻⁹–1.03×10⁻⁶ MSC ) and CaCl₂ (2×10⁻⁴–1.28×10⁻² MSC )-induced contractions in rat thoracic aorta. Furthermore, this extract induced relaxant effects in rat aorta precontracted with NA (10⁻⁶ MSC ) and with K⁺ (80 mMSC ). Two different vasodilator responses were observed on NA-induced contractions: one an endothelium-dependent response abolished by methylene blue but not by indomethacin, and the other an endothelium-independent response unaffected by methylene blue and indomethacin similar to that obtained with a flavone, luteolin (10⁻⁵ MSC ). The search for active constituents included a bioactivity-directed fractionation of the lyophilized aqueous extract (LAE) using vascular reactivity experiments. Four different fractions (Cl₂CH₂, Me₂CO, MeOH, H₂O) were analysed at two different concentrations (1 and 2 mg (dry plant)/mL). The methanol fraction was the most active on NA precontracted vascular segments with endothelium, whereas the water fraction was the most active on segments without endothelium. These relaxant effects were less on K⁺ (80 mMSC )-induced contractions. Due to these results we suggest that this plant contains interesting hydrophilic compounds with strong pharmacological action. The endothelium-independent relaxant effect is probably related to flavonoid constituents. However we cannot relate the endothelium-dependent relaxation to known natural compounds in Cistus species. The presence of these constituents with relaxing properties on smooth muscle could account for the use of Cistus plant in traditional medicine.     

Pharmacological activity of the extracts of two Satureja obovata varieties on isolated smooth muscle preparations

Aqueous extracts of two varieties of Satureja obovata Lag. subsp. obovata: var. valentina and var. obovata, exhibited a dose-dependent inhibitory effect on the contractions induced by acetylcholine (Ach) (3.4 × 10^?8?6.8 × 10^?5M) and CaCl₂ (2 × 10^?4?1.28 ? 10^?2M) in rat duodenum and by noradrenaline (NA) (10^?9?5.12 × 10^?7 M) and CaCl₂ (2 × 10^?4?1.28 × 10^?2 M) in rat aorta. The extracts also produced relaxant effects in both tissue preparations precontracted with K⁺ (75 mM) and in rat aorta precontracted with NA (10^?6 M). Vasodilatory effects of the two extracts were attenuated when the endothelium was removed. The inhibitory effects of var. valentina were stronger. These results indicated a smooth muscle relaxant effect that could account for the use of these extracts in traditional medicine.     

Double directional adjusting estrogenic effect of naringin from Rhizoma drynariae (Gusuibu)

Ethnopharmacological relevance

Chinese traditional medicine Rhizoma drynariae (Gusuibu) is widely used for clinically treating osteoporosis and bone non-union. Naringin and its active metabolite naringenin are the main active ingredients of Rhizoma drynariae total flavonoids.

Aim of the study

The purpose of this paper is to confirm estrogenic and anti-estrogenic activity of naringin and naringenin, and provide the basic data to further study for the dose-effect relationship and the mechanism for Rhizoma drynariae in treatment of osteoporosis and other estrogen deficiency-related diseases.

Materials and methods

Naringin was extracted from Rhizoma drynariae. Naringin and its metabolin naringenin were tested estrogenic and anti-estrogenic activities through the experiment of cell proliferation and uterus weight gain in mice. Their estrogen-receptor binding abilities were tested by yeast two-hybrid experiment and nuclear receptor cofactor assays (RCAS) experiment, and their possible binding sites for ERβ were performed by computer aided molecular docking technology.

Results

Naringin and naringenin showed significant effects on the proliferation of estrogen-sensitive ER(+) MCF-7 cells in the absence of estrogen. Induction increased proliferation as the drug concentration, and the strongest proliferation appeared at a concentration of 8.6 × 10⁻⁵ M. When estradiol (10⁻¹⁰ M) and the different concentrations of naringin or naringenin were treated at the same time, naringin and naringenin could result in antagonistic effects on estradiol-induced MCF-7 cell proliferation, but they did not significantly affect proliferation of estrogen-insensitive ER(−) MDA-MB-231 cells. Naringin and naringenin exhibited higher binding capacity to estrogen receptor β (ERβ) than estrogen receptor α (ERα) in yeast two-hybrid experiments and nuclear receptor cofactor assays (RCAS) experiment. Docking simulation between naringin/naringenin and ERβ were performed, and the corresponding binding free energies of naringin-receptor and naringenin-receptor docked complexes were −7.95 and −10.45 kcal/mol. Hydrogen bonds were found between naringin and the amino acid residues Lys304 and His308. The oxygen atom (O11) of naringenin formed hydrogen bond to Arg346, and there may be hydrophobic space interactions between phenyl group (C13-C18) of naringenin and the amino acid residues Leu298, Met336, Met340, Phe356, Ile376 and Leu380.

Conclusions

Naringin and naringenin revealed a double directional adjusting function of estrogenic and anti-estrogenic activities. Both of them showed estrogenic agonist activity at low concentration or lack of endogenous estrogen. On the other hand, they also acted as estrogenic antagonists at high concentrations or too much endogenous estrogen. They produced estrogenic and anti-estrogenic effects primarily through selectively binding with ERβ, which could prevent and treat osteoporosis with the mechanism of estrogenic receptor agitation. This paper confirmed the estrogenic and anti-estrogenic activity of naringin and naringenin, and further studies were still essential to study their dose-effect relationship and the anti-osteoporosis mechanism for Rhizoma drynariae in the treatment of osteoporosis and other estrogen deficiency-related diseases.     

Inhibiting Activity of Some Glucoindolalkaloids and Iridoids from Sickingia williamsii on Electrically Induced Contractions of Isolated Guinea-pig Ileum

The present study examined the effects of the extracts (petroleum ether, CHCl₃, CHCl₃/MeOH (9:1) and MeOH), partially purified fractions and pure compounds (mainly alkaloids and iridoids) from Sickingia williamsii on the electrically induced contractions of the isolated guinea-pig ileum. The results of our experiments indicate that CHCl₃/MeOH (9:1) and CHCl₃ extracts, tested at concentrations of 300, 150 and 30 μg/mL, dose-dependently reduced the guinea-pig ileum electrical contractions, whereas MeOH and petroleum ether extracts did not affect it. Furthermore, both the partially purified fractions I–IV each tested at concentrations of 500, 250 and 100 μg/mL from the CHCl₃/MeOH (9:1) extract and some pure compounds (10⁻⁴ M , 5×10⁻⁵ M and 2.5×10⁻⁵ M ) isolated and purified from the above fractions significantly reduced, in a dose dependent manner, the electrical contractions of the ileum. As the active pure compounds possess an indole nucleus or/and an iridoid nucleus in their structures, the inhibitory effects appear to depend on these structures.     

The interactions of paeoniflorin and veratrine on isolated rat atria

In this study, we attemped to identify the interactions and mechanisms between veratrine and paeoniflorin on isolated rat atria. Paeoniflorin alone showed no effect on the rat atria. Veratrine increased the atrial contraction and induced arrhythmia at 1×10⁻⁵ g/ml. Veratrine could directly induce contraction and elicit tetanic contraction at 1×10⁻⁴ g/ml in the left atria with or without electric stimulation. Paeoniflorin (4.8×10⁻⁶ to 4.8×10⁻³ g/ml), verapamil (2.2×10⁻⁶ g/ml), tetrodotoxin (TTX) (3.2×10⁻⁸ g/ml) and quinidine (7.5×10⁻⁶ g/ml) inhibited the increase of contraction and delayed the onset of contraction induced by veratrine (1×10⁻⁵ g/ml). The inhibitory effect of paeoniflorin combined with verapamil on the contraction induced by veratrine was more potent than that of paeoniflorin or verapamil alone. However, the inhibitory effect of paeoniflorin was not potentiated by TTX or quinidine. From the above results, the contraction evoked by veratrine in the rat atria may be concluded to be caused by the stimulation of Na⁺- and Ca²⁺-ion channels. The inhibition of paeoniflorin on the contraction induced by veratrine may primarily be related to the blockade of Ca²⁺ channels.     

Effects of Crocus sativus petals' extract on rat blood pressure and on responses induced by electrical field stimulation in the rat isolated vas deferens and guinea-pig ileum

We have investigated the effects of Crocus sativus petals' extract on blood pressure in anaesthetised rats and also on responses of the isolated rat vas deferens and guinea-pig ileum induced by electrical field stimulation (EFS). Aqueous and ethanol extracts of C. sativus petals reduced the blood pressure in a dose-dependent manner. For example administration of 50 mg/100 g of aqueous extract changed the blood pressure from 133.5+/-3.9 to 117+/-2.1 (mmHg). EFS of the isolated rat vas deferens and guinea-pig ileum evoked contractions were decreased by aqueous and ethanol extracts of C. sativus petals. The aqueous extract (560 mg/ml) significantly reduced the contractile responses of vas deferens to epinephrine (1 microM) without any change in contraction induced by KCl (300 mM). The present results may suggest that the relaxatory action of C. sativus petals' extract on contraction induced by EFS in the rat isolated vas deferens is a postsynaptic effect.     

人参皂甙对大鼠输精管和肛尾肌中α受体效应的影响

人参皂甙(G,10~(-4)g/ml)对离体大鼠输精管(RVD)的正常张力无影响,但能增强电场刺激引起的RVD收缩效应,对抗可乐定(Clo)抑制和育亨宾(Yoh)增强电场刺激引起的RVD收缩。G使苯福林(Phe)对RVD和肛尾肌(RAM)α_1受体作用的量效曲线右移。上述结果进一步支持G在突触前后膜α受体水平上可能均起着调谐剂(modulator)样作用的观点。     

The source of ca2+ for the spasmolytic actions of longicaudatine,a bisindole alkaloid isolated from Strychnos trinervis (Vell.) Mart. (Loganiaceae)

Longicaudatine, a tertiary bisindole alkaloid isolated from the root bark of Strychnos trinervis (Vell.) Mart. (Loganiaceae), antagonized in a noncompetitive manner, carbachol and histamine induced contractions of the guinea-pig ileum and bradykinin responses in the rat uterus. The respective pD₂' values (mean ± SE) were 4.61 ± 0.21, 4.98 ± 0.04 and 4.49 ± 0.01. Longicaudatine, unlike verapamil, had no effect on voltage dependent Ca²⁺ channels, as it failed to inhibit KCI or CaCl₂ induced contractions of guinea-pig ileum and depolarized rat uterus respectively. When compared with sodium nitroprusside, an antagonist of receptor operated Ca²⁺ channels, longicaudatine produced a slower and weaker inhibition of noradrenaline induced sustained contractions of rabbit aortic strips. However, in the aorta, the alkaloid antagonized the intracellular calcium dependent transient contractions of noradrenaline and longicaudatine (IC₅₀, 5.01 × 10^?7 M) was approximately 133 times more potent that procaine (IC₅₀, 6.68 × 10^?5 M), a known inhibitor of the release of Ca²⁺ from intracellular stores. Longicaudatine may exert nonspecific spasmolytic effects by acting on intracellular Ca²⁺ stores, rather than on depolarization dependent or receptor operated Ca²⁺ channels.     

Bisnordihydrotoxiferine and vellosimine from Strychnos divaricans root: Spasmolytic properties of bisnordihydrotoxiferine

Bisnordihydrotoxiferine and vellosimine, two tertiary indole alkaloids have been isolated from the root of Strychnos divaricans. Bisnordihydrotoxiferine antagonized in a nonspecific manner, oxytocin and acetylcholine induced contractions in the rat uterus and acetylcholine and histamine responses in the guinea-pig ileum. Bisnordihydrotoxiferine, like verapamil, produced effects on voltage dependent Ca²⁺ channels. For example in guinea-pig ileum, bisnordihydrotoxiferine (pD'₂ 3.92±0.09) and verapamil (pD'₂ 6.00±0.11) inhibited KCl induced contractions. Furthermore, bisnordihydrotoxiferine (pD'₂ 4.37±0.02) and verapamil (pD'₂ 6.83±0.10) also antagonized CaCl₂ induced contractions of K⁺-depolarized rat uterus. When compared with sodium nitroprusside, an antagonist of receptor operated Ca²⁺ channels, bisnordihydrotoxiferine had no effect. However, in the aorta, the alkaloid (IC₅₀, 6.10 × 10^?6M) antagonized the intracellular calcium dependent transient contractions of noradrenaline and it was about four times more potent than procaine (IC₅₀, 2.30 × 10^?5M), a known inhibitor of the release of Ca²⁺ from intracellular stores. Bisnordihydrotoxiferine may produce nonspecific spasmolytic actions mainly by inhibiting intracellular calcium mobilization and to a lesser extent by inhibiting voltage dependent calcium channels in smooth muscles.     

Chemical and pharmacological analysis of the crude aqueous/alcoholic extract from Cordyline dracaenoides

Chemical analysis of Cordyline dracaenoides (Kunth) demonstrated the presence of steroidal saponins and anthocyanidins in the stem, rhizome and root. Small amounts of tannins were also detected in its stem and rhizome. Pharmacological analysis revealed different effects according to the part of the plant used. Crude aqueous/alcoholic extract (CE) from the rhizome inhibited carrageenan-induced rat paw oedema, while the CE obtained from the root significantly decreased the locomotor activity and potentiated barbiturate-induced hypnosis in mice. The CE from the roots inhibited noradrenaline-induced contraction in the rat vas deferens in a concentration-dependent and a noncompetitive manner, while the CE from the rhizome caused a parallel displacement to the left of noradrenaline concentration response curves. In the isolated rat stomach, the CE from the roots promoted a concentration-dependent displacement to the right of the serotonin concentration response curve allied to a marked inhibition of its maximal response, while the CE from the rhizome produced only an inhibition of about 40% of serotonin-contractile responses. These results suggest that the CE from C. dracaenoides exhibits a potent and long lasting antioedematogenic effect, has central depressant effects and potentiates noradrenaline-induced contractile responses of the isolated rat vas deferens. All these effects may be, at least in part, related to the presence of steroidal saponins in this plant.     

Hypotensive activity of Thymus orospedanus alcoholic extract

The hypotensive effects of the alcoholic extract of Thymus orospedanus were investigated in both in vivo and in vitro assays. Our results indicate that the extract reduced rat blood pressure and modified the dose–response curve to epinephrine in the rat vas deferens and the rabbit artery, indicative of a competitive antagonism.     

Endothelium-dependent vasodilator effect of extract prepared from the seeds of Areca catechu on isolated rat aorta

Arecae semen extract relaxed aortic ring preparations of isolated rat aorta that contained endothelium from 3×10⁻⁷ g/mL, reaching a maximum of 86% at 10⁻⁵ g/mL. Its relaxation did not occur in specimens without endothelium, and was inhibited by pretreatment with 10⁻⁴ M N^G-nitro-1-arginine methylester. One of the active components was arecoline which is a muscarinic receptor agonist. Another active component was condensed tannin contained in Arecae semen. © 1997 John Wiley & Sons, Ltd.     

Xanthine Oxidase Inhibitory Activity of Flavonoids and Tannins from Hexachlamys edulis (Myrtaceae)

The acetone-water extract of Hexachlamys edulis (Myrtaceae) inhibited the enzyme xanthine oxidase (XO) in vitro . Bioassay-guided isolation led to the gallic acid ester in 2″ of myricitrin (desmanthin-1), (-)-epigallocatechin-3-O-gallate (EGG) and pentagalloylglucose as the main XO inhibitors of H. edulis . Desmanthin-1 and EGG were mixed-type inhibitors of XO with K _i values of 1.6×10⁻⁴ M and 1.8×10⁻⁴ M , respectively. Pentagalloylglucose was an uncompetitive XO inhibitor with a K _ESI of 6.7×10⁻⁶M . From the active n -butanol soluble part of the aqueous acetone extract of H. edulis , several flavonoids were isolated. The flavonoids were mainly myricetin-3-O-monoglycosides with the quercetin glycoside avicularin as a minor compound displaying a weak inhibitory activity towards XO.     

Biological Activity and Xanthine Oxidase Inhibitors from Scirpus californicus (C. A. Mey.) Steud.

The methanol extract of the rhizomes of Scirpus californicus (Cyperaceae) inhibited the enzyme xanthine oxidase (XO) in vitro . Bioassay-guided isolation led to piceatannol, scirpusin A and scirpusin B as the main XO inhibitors of S. californicus. Piceatannol, scirpusin A and B were mixed-type inhibitors of the XO with K _i values of 1.1×10⁻⁴, 6×10⁻⁴ and 5×10⁻⁵ M , respectively. The extract and above mentioned compounds were marginally active as hypotensors when tested in normotensive rats at 2.5 mg/kg and were inactive towards the DNA binding assay in vitro.